A checksum is data stored in a file and is general computer technology:

A value that is computed and that depends on the contents of a set of data. Checksums are stored or transmitted with the data. The checksum is used to detect if the data has been altered during transmission or when being stored and retrieved. Receiving programs recompute the checksum to compare with the checksum sent or stored with the data. Checksums may be more than one digit. They are not always the result of addition but may be the result of one or more computations involving addition' date=' subtraction, multiplication, or division"[/quote']

...and this is how a dealer/Skoda HQ/insurance companies could tell that the car had been remapped - even if the original code is put back into the ECU?

Even if the original code has been put back on the ECU, might there be stored readings in the ECU which are outside the parameters of the stock map and would indicate that things are/were not as they should be, eg boost, RPM, diagnostic trouble codes (fault codes) or whatever?

...and this is how a dealer/Skoda HQ/insurance companies could tell that the car had been remapped - even if the original code is put back into the ECU?

I think that it will depend how the ecu is copied or if it is cloned. In the IT world if you clone a file the checksum for that file will be the same as when it is originally created but you may beable to find out if the storage device has been cloned in this case the ECU. If you get what I mean

Another factor to consider is that if an insurance company/dealer suspects you of committing fraud by not declaring a map, there are other ways they could prove you had the work done (invoices, credit card statements, mobile phone locations, CCTV appearances, posts on this forum, etc.). Admittedly you'd have to be looking at a seriously big claim for them to bother going to these lengths, but it *is* a possibility.

As has been wisely said earlier on this thread, if you can't pay, don't play...

Rob.

Another factor to consider is that if an insurance company/dealer suspects you of committing fraud by not declaring a map' date=' there are other ways they could prove you had the work done (invoices, credit card statements, mobile phone locations, CCTV appearances, posts on this forum, etc.). Admittedly you'd have to be looking at a seriously big claim for them to bother going to these lengths, but it *is* a possibility.

As has been wisely said earlier on this thread, if you can't pay, don't play...

Rob.[/quote']

:iagree:

Another factor to consider is that if an insurance company/dealer suspects you of committing fraud by not declaring a map' date=' there are other ways they could prove you had the work done (invoices, credit card statements, mobile phone locations, CCTV appearances, posts on this forum, etc.). Admittedly you'd have to be looking at a seriously big claim for them to bother going to these lengths, but it *is* a possibility.

As has been wisely said earlier on this thread, if you can't pay, don't play...

Rob.[/quote']

Totally agree... I'm just trying to work out what goes on when an ECU is remapped... :confused:

I think that there are a number of chips in the ECU box. One of these is dedicated to the engine map and it is this which is recoded/remapped/replaced or whatever. Earlier Jabba remaps involved removing that chip and replacing it with one mounted on a small motherboard (emulator) which enabled it to be remapped and recognised by the ECU. (Something to do with keeping the checksum the same, I think). I'm pretty sure that Jabba now remap the existing chip, at least as far as the 1.8T fitted in the Octavia is concerned.